PAC BB-4PR Pair of 4" Bass Blocker Easily handles power of up to 50 watts Orange color coded leads for easy identification Encased in heat shrink tubing with wire leads for easy installation Pair of bass blockers Removes selected frequencies from the audio source Frequencies blocked: 4 ohms: 0-1200 Hz / 8 ohms: 0-600 Hz Protects the speakers from receiving damaging frequencies Designed for use with 4" speakers